Role of efflux pump and OprD porin expression in carbapenem resistance of Pseudomonas aeruginosa clinical isolates

Abstract

Introduction: In recent years, the prevalence of multidrug-resistant P. aeruginosa has remarkably increased. Thus, we wanted to investigate the carbapenem resistance mechanisms and clonal relationship among 80 carbapenem-resistant P. aeruginosa strains. Methodology: Carbapenemase production was detected using the Modified Hodge Test (MHT), EDTA combined disc method (ECD), and PCR. Expression levels of efflux and porin genes were mesured by real-time reverse transcription PCR. Clonal relationship of the isolates was investigated by pulsed-field gel electrophoresis (PFGE). Results: Carbapenemase production was detected in 7.5% of the isolates with MHT/ECD tests and in 11.3% of the isolates with PCR. Although the specificity of MHT/ECD was high, the sensitivitivity was low. oprD downregulation and mexB, mexY, and mexD overexpression were demonstrated in 55%, 16.3%, 2.5%, and 2.5% of the isolates, respectively. Multiple carbapenem resistance mechanisms were found in nearly a quarter of the isolates. PFGE typing of the 80 P. aeruginosa isolates yielded 61 different patterns. A total of 29 isolates (36.3%) were classified in 10 clusters, containing 2 to 7 strains. We could not find a strict relationship between PFGE profile and carbapenem resistance mechanisms. Conclusions: Although oprD downregulation and MexAB-OprM overexpression were the most common mechanisms, carbapenem resistance was associated with multiple mechanisms in the study. MHT/ECD tests should not be used alone for investigation of carbapenemase production in P. aeruginosa. Rapid tests with high sensitivity and specificity should be developed for the detection of carbapenemase production in P. aeruginosa.

<p>Molecular Epidemiology and Mechanisms of High-Level Resistance to Meropenem and Imipenem in <em>Pseudomonas aeruginosa</em></p>

“…39 Although the MexXY-OprM system is known as a substantial element in aminoglycoside resistance in only P. aeruginosa, 40 it is also over-expressed in multi-drug resistant P. aeruginosa 41 and similar reports to our study have shown its over-expression in carbapenemresistant P. aeruginosa strains. 7,42,43 MexAB-OprM over-expression was observed in 21.8% of the isolates, concurring with Xavier and co-workers. 44 In contrast, Dantas et al 7 and Chalhoub et al 32 reported a much higher frequency of MexAB-OprM over-expression in P. aeruginosa isolates.…”

“…44 In contrast, Dantas et al 7 and Chalhoub et al 32 reported a much higher frequency of MexAB-OprM over-expression in P. aeruginosa isolates. Surprisingly, no down-regulation of oprD was detected in this study, which could be claimed to the presence of mutations eg, in loops L2 and L3 as described by Muderris et al 45 However, Chalhoub et al found no role for oprD mutation in high-level resistance compared to efflux pump overexpression. 32 Finding bacterial genetic similarity and relatedness is crucial for cross-infection assessment, for which the value of various genotyping techniques has been recognized.…”

It’s Not Easy Being Green: A Narrative Review on the Microbiology, Virulence and Therapeutic Prospects of Multidrug-Resistant Pseudomonas aeruginosa

“…The modes of antibiotic resistance in P. aeruginosa may be classified into three categories, including (i) adaptive (i.e., biofilm formation, dormant forms), (ii) intrinsic (see Table 2), and (iii) acquired resistance mechanisms (mutation or acquisition of integrons, plasmids, prophages, and transposons by the means of HGT), resulting in a rich and diverse resistome [161]. The occurrence of mutations may lead to antibiotic uptake reduction, antibiotic target modifications, and over-expression of both efflux pumps system and antibiotic inactivating enzymes [162][163][164]. In essence-apart from the fluoroquinolones (who present with excellent oral bioavailability)-all of the present therapeutic alternatives for P. aeruginosa need to be administered parenterally [165].…”

“…Intrinsic resistance and relevant therapeutic alternatives in Pseudomonas infections[159][160][161][162][163][164][165].…”

A Extensively drug-resistant Pseudomonas putida bacteremia that was resolved spontaneously

“…In our country, most common carbapenem resistance mechanisms in P. aeruginosa infection are the ones mediated by metalloβ-lactamase (MBL) and OXA-23 carbapenemase enzymes but also oprD downregulation and mexB, mexY, and mexD overexpression were demonstrated. [30][31][32][33][34].…”